If we have two pistols of the same type same caliber, everything is the same EXCEPT the barrel length, is it possible to calculate the difference in the amount of powder one needs? For example, if a .40 pistol that has a 8 inch barrel that turns out to require 10g, does a 4 inch barrel sister pistol only requires 5g, while a 12" barrel requires 15g? Is the equation linear, or curve, assuming everything is the same? If everything is the same in the same situation, BUT a different twist rate, would that also affect the amount o powder needed? Is it possible to calculate or at this point it is a trial and error art form?
Barrel length vs grains
- Thread starter conradin
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Longer barrels may benefit from using a slower burning powder as it has more barrel to contain the combustion. And shorter barrels may benefit from a faster burning powder as you ideally want to burn all the powder within the barrel length.
Simply dropping the powder charge for a shorter barrel while using the same powder is going to make a lighter load. The shorter barrel is likely going to show less velocity anyway, so dropping the same powder is going to make it even slower.
Twist rate, unless it is significantly different, is not going to affect things in a big way.
Simply dropping the powder charge for a shorter barrel while using the same powder is going to make a lighter load. The shorter barrel is likely going to show less velocity anyway, so dropping the same powder is going to make it even slower.
Twist rate, unless it is significantly different, is not going to affect things in a big way.
Crawdad1
Member
No two rifles barrels are the same. Each and every one of them is an individual that needs to be shot to find out the loading it likes. You could possibly use your calculation as a stating point but that's about it.
Twist rate is not going to have a big effect unless its really tighter or loose. For example, I load for my 308 winchester and some manuals call for a 1:12 twist rate and some are 1:10. Unless you are loading way on the ragged edge using a 1:12 data and have 1:10 twist, you aren't going to see a significance in pressure. Crawdad is correct-its really going to depend more on the individual barrel
zimmerstutzen
Member
The is a formula for maximum powder-energy efficiency. But it skews of for calibers under 44 and over 54. The problem with heavy 40 cal loads in the short barrel is that ythe room for the powder charge takes up barrel space leaving the projectIle less room to accelate before muzzle exit.
whughett
Member
This thread is confusing. Op seems to be talking about smokeless loads in a handgun. Are we talking about rifles, hand guns, smokeless or black powder.
Handgun barrel lengths, rate of twist or ...........................
Handgun barrel lengths, rate of twist or ...........................
AJumbo
Member
The differences you're concerned with don't present any practical difference. Go shoot your guns; you can't beat real experience, no matter ho fancy your slide-rule is.
EljaySL
Member
Basically if you buy a black powder gun once you've shot it a bit and it's broken in a bit and you're used to it, you just adjust the load in 5gr increments, shooting a group at each point, and see what the accuracy does.
If you're a target shooter you optimize for accuracy, and then holding that powder level constant you adjust one more parameter at a time - minor changes to ball size, patch thickness, type of lube, amount of lube...
If you're a hunter you find the maximum load that gives an acceptable level of accuracy, whatever that means to you.
If I see, say, 25gr and 30gr are a tie for most accurate I'll also try 27.5 gr to a) make sure it's not more accurate, and to b) try to make sure I'm in the middle of the sweet spot. There's usually a really broad sweet spot so it's not like a grain here or there will matter as much as the other variables (the patch, etc).
If you're a target shooter you optimize for accuracy, and then holding that powder level constant you adjust one more parameter at a time - minor changes to ball size, patch thickness, type of lube, amount of lube...
If you're a hunter you find the maximum load that gives an acceptable level of accuracy, whatever that means to you.
If I see, say, 25gr and 30gr are a tie for most accurate I'll also try 27.5 gr to a) make sure it's not more accurate, and to b) try to make sure I'm in the middle of the sweet spot. There's usually a really broad sweet spot so it's not like a grain here or there will matter as much as the other variables (the patch, etc).
Not sure what you mean by the amount of powder one needs? Needs to of what? Hunt? Target shoot?
At the lengths you describe the shortest would probably use less powder as with black powder the excess above a certain amount wouldn't burn before the bullet left the barrel. But how much didn't burn would depend on a host of conditions like type and quality of the powder, humidity level and how the powder was stored or carried ( black powder being hydroscopic), batch quality, etc.
At the lengths you describe the shortest would probably use less powder as with black powder the excess above a certain amount wouldn't burn before the bullet left the barrel. But how much didn't burn would depend on a host of conditions like type and quality of the powder, humidity level and how the powder was stored or carried ( black powder being hydroscopic), batch quality, etc.
J-Bar
Member
One way to determine maximum effective powder charge in a rifle is to spread a white sheet on the ground in front of your shooting bench and look for unburned powder grains on the sheet after you make a shot. When you see unburned powder grains on the ground, you have exceeded your maximum effective load for that rifle.
I guess the same approach for determining maximum charges could be applied to a revolver. Personally, I think it's more fun to shoot for tightest groups, which is usually less than maximum charge. And since every gun is a snowflake, that is going to vary from gun to gun, regardless of barrel length.
I guess the same approach for determining maximum charges could be applied to a revolver. Personally, I think it's more fun to shoot for tightest groups, which is usually less than maximum charge. And since every gun is a snowflake, that is going to vary from gun to gun, regardless of barrel length.
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